A variety of uniform nanocrystals (NCs) and heterostructured materials with different sizes, shapes, and compositions can be prepared with nanometer precision using surfactant-assisted organic- or aqueous-based techniques. This nanoscale control over a wide variety of different crystallographic surfaces and compositions is very appealing for catalytic studies because it allows accurate structure-activity relationships and mechanisms to be made. Studying finely controlled NC systems is important for answering fundamental questions that could allow the preparation of more active catalysts. These well-defined systems are also very active catalysts, due to the increased density of specific, highly reactive sites. In addition to the above mentioned advantages in catalytic processes, the high uniformity allows to use ensemble-averaged techniques such as x-ray spectroscopies to obtain reliable information about the entire sample under investigation. This aspect is a great advantage given the opportunity to merge microscopic and macroscopic information with catalytic data to derive in-depth knowledge of catalytic active sites. In this contribution, selected examples of nanostructured catalysts made from well-defined nanocrystals will be presented, together with opportunities in using x-ray techniques (mainly EXAFS) in combination with microscopy and catalytic studies to investigate catalytic processes at the nanoscale with consequences for the overall performance of the samples. In particular, the study of catalyst restructuring under reaction conditions will be the focus of this talk, showing how Pd- and Ru-based catalysts change in size and structure with profound consequences for the catalytic activity and selectivity in methane combustion and CO2 hydrogenation reactions.

Well-defined nanocrystals catalysts as active phases and premier materials for spectroscopic studies of catalyst restructuring

256th National Meeting (2018)

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